diff --git a/libs/libpcf/src/base/pcf2place.cpp b/libs/libpcf/src/base/pcf2place.cpp
index 7895667e76..539aa0a374 100644
--- a/libs/libpcf/src/base/pcf2place.cpp
+++ b/libs/libpcf/src/base/pcf2place.cpp
@@ -41,6 +41,8 @@ int pcf2place(const PcfData& pcf_data,
     VTR_LOG("PCF basic check passed\n");
   }
 
+  /* Map from location to net */
+  std::map<std::array<size_t, 3>, std::string> net_map;
   /* Build the I/O place */
   for (const PcfIoConstraintId& io_id : pcf_data.io_constraints()) {
     /* Find the net name */
@@ -102,6 +104,20 @@ int pcf2place(const PcfData& pcf_data,
       continue;
     }
 
+    std::array<size_t, 3> loc = {x, y, z};
+    auto itr = net_map.find(loc);
+    if (itr == net_map.end()) {
+      net_map.insert({loc, net});
+    } else {
+      VTR_LOG_ERROR(
+        "Illegal pin constraint: Two nets '%s' and '%s' are mapped to the I/O "
+        "pin '%s[%lu]' which belongs to the same coordinate (%ld, %ld, %ld)!\n",
+        itr->second.c_str(), net.c_str(), int_pin.get_name().c_str(),
+        int_pin.get_lsb(), x, y, z);
+      num_err++;
+      continue;
+    }
+
     /* Add a fixed prefix to net namei, this is hard coded by VPR */
     if (IoPinTable::OUTPUT == pin_direction) {
       net = "out:" + net;